llog.js

index.js

// To add this Gist to a project:
// 
//     npm install https://gist.github.com/25fad725870b0ada74df2bce7d115cc1.git

/**
 * @param {number} level
 */
exports.trace = function (level) {
  const obj = {}
  const lim = Error.stackTraceLimit
  Error.stackTraceLimit = level + 1
  Error.captureStackTrace (obj)
  Error.stackTraceLimit = lim
  const re = /^    at ([^\n]+)?$/mg
  // “    at Object.nai [as fun] (NovelAI.js:83:13)”
  // “    at exports.trace (c:\Users\...\llog\index.js:12:9)”
  // “    at c:\...\grab\grab.js:40:3”
  const rel = /[\w:\.\\\/-]*?([\w-]+)\.js:(\d+):\d+\)?$/
  let ma, mam; for (let ix = level; 0 < ix; --ix) {
    ma = re.exec (obj.stack)
    if (ma == null) return null
    mam = rel.exec (ma[1])
    if (false) console.log (ix, ma[1], mam)
    if (mam == null) return null}
  return mam}

/** @type {Map<string, number>} */
let COUNTER

/**
 * @param {string} uid Location to globally count to, or any other ID
 * @returns {number} Count towards how many times we were already at `loc`
 */
exports.count = function (uid) {
  if (COUNTER == null) COUNTER = new Map()
  const count = (COUNTER.get (uid) ?? 0) + 1
  COUNTER.set (uid, count)
  return count}

/**
 * @param {number} times How many times to return true to the call site
 * @returns {boolean} False if the call site evaluated it `times`
 */
exports.times = function (times) {
  const ma = exports.trace (3)
  if (ma == null) return null  // Can't count
  const loc = ma[1] + ':' + ma[2]
  const count = exports.count (loc)
  return count <= times}

/**
 * Log a `line` prepending the current file name and line number  
 * Works in NodeJS but probably not in a browser
 * @param {any} line
 * @param {number} [times] Log only N `times` from that location
 */
function log (line, times) {
  const ma = exports.trace (3)
  if (ma == null) {
    log.out (line)
  } else {
    const loc = ma[1] + ':' + ma[2]
    if (times) if (exports.count (loc) > times) return
    log.out (line, loc)}}

/**
 * Override to change destination
 * 
 * @example
 * const date = require ('date-and-time');
 * const {log} = require ('log');
 * log.out = (line, loc) => console.log (date.format (new Date(), 'DD HH:mm]'), (loc ?? '') + ']', line)
 */
log.out = function (line, loc) {loc ? console.log (loc + ']', line) : console.log (line)}

exports.log = log

/**
 * Sleep for the given number of milliseconds
 * @param {number} ms
 */
exports.snooze = function (ms) {return new Promise (resolve => setTimeout (resolve, ms))}

/** 
 * NB: Different from `console.assert` in that we're throwing a “normal” `Error`
 * which unwinds, interrupting the program
 * @param {boolean} condition
 * @param {() => string} [message]
 */
exports.assert = function (condition, message) {
  if (condition) return
  const locᵃ = exports.trace (3)
  const loc = locᵃ ? locᵃ[1] + ':' + locᵃ[2] : '_'
  if (message) throw new Error ('[' + loc + '] Assertion failed: ' + message())
  throw new Error ('[' + loc + '] Assertion failed')}

exports.hash = s=>{for(var i=0,h=9;i<s.length;)h=Math.imul(h^s.charCodeAt(i++),9**9);return h^h>>>9}

package.json

{
  "name": "llog",
  "version": "1.1.1",
  "description": "log to console with line number attached",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "contributors": [
    "Artemciy"
  ],
  "repository": {
    "type": "git",
    "url": "https://gist.github.com/25fad725870b0ada74df2bce7d115cc1.git"
  },
  "license": "MIT"
}